Shading Intensity Research Articles

STORAGE OF TREMA (Trema orientalis Linn. Blume) SEEDLINGS IN NURSERIES AND THEIR EFFECT ON GROWTH

Trema ( Trema orientalis Linn. Blume) is one of forest tree species that has potency to be used as a renewable biomassa energy source. The successful of the development of this species is strongly depent on the quality and quantity of the seedlings. The problems often occur when the seedlings should be stacked up in a nursery due to the unreadiness of the planting sites and rainy season. Therefore, the seedlings should be stored and managed by suppressing their growth during storage. The aim of the study is to examine the growth responses of trema seedlings to the treatments of growth retardants and shade during storage in the nursery and replanting in the field. Slow growth method was used in this study by applying growth inhibitors (250 ppm paclobutrazol, 0.5% NaCl) and regulating shade conditions (90% shade, 50% shade and no shade) and stored for 6 months. After storing in the nursery, treated seedlings were replanted in the field and observing for their growth for 17 months. The results showed that the growth of the seedlings could be suppressed for 6 months by applying 250 ppm paclobutrazol under 50% shade condition (T=32.2˚C; RH=62%, light intensity of 27,300 flux). This condition suppressed the growth of the diameter and root shoot ratio by an average of 49% and 11% respectively, and maintain the seedling survival up to 97.67%. The best growth in height and diameter in the field was achieved by a combination of treatment using NaCl with a shade intensity of 50%. It is concluded that the effectiveness of the application of inhibitors on trema seedlings when were stored in the nursery was different from that used to increase the growth of trema in the field.

Shade tree canopy cover affects coffee plant traits across elevations in coffee farms in southwest Ethiopia

Coffee is an important crop in the global south. However, ongoing changes in the climate system reinforce the need to quantify coffee plants' ecological and eco‐physiological traits to assure coffee production in the future. One way to assess how environmental changes affect coffee performance is via leaf traits, most notably leaf carbon and nitrogen concentrations (to reflect the nutrient status), leaf stable carbon isotope composition (δ13C) to determine intrinsic water use efficiency (WUEi), and specific leaf area (SLA) to describe carbon gain relative to water loss within a plant canopy as these traits are related to yields. Therefore, we sampled coffee plants growing at contrasting elevations using a space‐for‐time substitution approach for warming and superimposed a canopy cover gradient to assess whether increasing canopy cover could modulate responses to temperature. Three coffee shrubs were sampled in each of 59 coffee farms in southwest Ethiopia across elevations of 1500–2160 m a.s.l. and along canopy cover gradients from open to deep shade. Soil nutrient concentrations, light availability, soil temperature and moisture were quantified for each coffee shrub. Elevation and shade tree canopy cover significantly and interactively affected WUEi. Elevation was found to be the driving factor for microclimate and soil factors which indirectly influenced both SLA and WUEi. Both of these coffee leaf traits are moderately governed by soil temperature whereas leaf N and C:N are mainly controlled by soil temperature and soil chemical variables. As elevation increased, WUEi kept increasing at light (< 35%) to intermediate shade levels (35–65%), and the values decreased at dense shade levels (65–100%) at high elevations, suggesting that coffee plants growing at high elevations with light shade can assimilate more CO2with minimum evaporative water loss. SLA declined with elevation. Leaf N and leaf C:N responded negatively and positively to shade canopy cover, respectively. In sum, elevation and canopy cover interactively determined microclimate and coffee leaf traits. Our findings are useful to adjust the intensity of shade, along with other tree‐level management tools, to modulate climate‐change effects on coffee at the farm level.

Disentangling effects of altitude and shade cover on coffee fruit dynamics and vegetative growth in smallholder coffee systems

Increases in temperature and more erratic rainfall patterns due to climate change threaten the already fragile livelihood of smallholder coffee farmers. Shaded coffee in agroforestry systems appear to be a good alternative to protect coffee from extreme temperatures while providing additional ecosystem services, such as extra food and soil protection. However, excessive shade might reduce coffee yields. This study analyzed the effect of shade cover (shade type represented by cropping system (Coffee-Open (CO), Coffee-Banana (CB), Coffee-shade tree (CT))), and shade intensity (represented by leaf area index of the shade cover) along an altitude gradient on: (i) microclimate, (ii) soil water content and (iii) coffee reproductive and vegetative growth. Data was collected during two coffee fruit development cycles (2015 and 2016) in smallholder coffee farms (n = 27) on the west slopes of Mt. Elgon Uganda. Shade cover buffered coffee trees from microclimate extremes (maximum temperature (- 3 °C) and temperature amplitude - 3 °C). Fruit set decreased with shade cover increases. Leaf set was shown to be the most important variable for vegetative and reproductive growth along several production cycles, and fruit drop was determined mainly by fruit set. Intermediated shade cover (LAI ~ 1 m2 m−2), as occurred in coffee intercropped with bananas, showed an optimal balance between microclimate regulations, fruit set, and fruit drop, and provided staple food and an extra source of income.

Pigments in flower stems of lisianthus under different photoselective shade nets

Abstract The lisianthus culture is demanded to produce cut flowers and pot vases, grown in a greenhouse using advanced techniques. The present study aimed to evaluate the pigments of different lisianthus cultivars in different photoselective shade nets. The cultivars Flare Deep Rose (pink), Echo Blue BL (purple) and Allemande White BI (white) were cultivated under light-diffusing polyethylene film cover and blue and red color photoselective nets with a shading capacity of 30%, in addition to the control treatment, without the use of the net. The results showed higher values of chlorophyll b and total in the red photoselective net, independent of the cultivar. Leaf colorimetry showed the most intense shade of green was from the cultivar Echo Blue BL. On the other hand, the control showed more intensity, with no significant difference in the leaf green intensity on the blue and red shade nets. In the petals, the cultivar Echo Blue BL showed a more intense blue shade in the red net, however low grade of anthocyanin than in the blue one. In the anthocyanin pigment, this cultivar had lower levels in the treatment of the red net. The results indicate that the use of photoselective shade nets in the culture of lisianthus changes the content of the pigments studied, in varying intensity, depending on the cultivar.

Screening of shade tolerant hybrid maize based on stress tolerance index

The development of adaptive and high-yielding maize varieties tolerant to shade stress is the right strategy to increase productivity and national maize production by utilizing the land in shaded conditions or under annual stands with 40% shade intensity. This study aimed to assess the best genetic material before releasing new shade tolerant maize varieties. This experiment was conducted in shaded and unshaded conditions in the Indonesian Cereal Research Institute, Maros, from July-October 2018 in KP. Pandu, North Sulawesi under coconut trees from March-August 2019. The design is using a randomized block design with three replications. The genetic material used consisted of 10 three-lane cross-hybrid maize, SHD01, SHD02, SHD03, SHD04, SHD05, SHD06, SHD07, SHD08, SHD09, and SHD10, and two comparison varieties of three-lane cross-hybrid maize, Bima-19, and P-35. Shade causes a reduction in light intensity, impacting changes in the microclimate under the shade. This is indicated by the dynamics of changes in light intensity which are quite high between maize crops in shaded and unshaded conditions. Tolerance to shade stress was assessed by measuring the difference in yield between unshaded environmental conditions and shaded environmental conditions to assess average productivity under normal and shaded conditions using the stress tolerance index (STI). The adaptive level in shade conditions of the candidate varieties SHD02 and SHD10 was significantly better than that of the Bima 19 and P 35 varieties, with the STI values of these candidates being 0.87 and 0.80, while the two comparison varieties Bima 19 and P 35, were respectively only 0.62.

Gogo rice agronomic patterns on water supply variables and light intensity

The study was aimed to find out the varieties of Gogo rice that are resistence of water supply and the low of light intensity and giving information about the varieties that are resistence of double water stress. The study was conducted on November 2020 to May 2021 and used a Randomized Block Design (RAK) with three factors. The first factor is soil water content of D1 40%, D2 60%, D3 80%., the second is shade intensity of N0 0%, N1 20%, N2 40%, and N3 60%. and the third is the varieties of V1 Situbagendit, V2 Red Sigambiri, V3 Inpago 8, V4 White Sigambiri. The result showed that there were differences of growing in different treatnent where the highest of plant of D3N0V1 is 54,73, the highest number of leaves of D3N0V1 is 7.03 and the highest tillers of D3N0V1 is 6.01. On each lowest observation of D1N2V4, the plants died at the age of 12 mds. The findings of the study showed that the soil water content of 80 %, and shade intensity of 0 % are significant effect on Gogo Varieties of Situbagendit.

Virtual pruning of 3D trees as a tool for managing shading effects in agroforestry systems

Light is a limiting resource for crops within integrated land use systems especially those including woody perennials. The amount of available light at ground level can be modified by artificially pruning the overstory. Aiming to increase the understanding of light management strategies, we simulated the pruning of wild cherry trees and compared the shading effects of the resulting tree structures over a complete growing season, with fine spatiotemporal resolution. Original 3D-tree structures were retrieved employing terrestrial laser scanning and quantitative structure models, and subjected to two pruning treatments at low and high intensities. By using the ‘shadow model’, the analogous tree structures created diverse shaded scenarios varying in size and intensity of insolation reduction. Conventional pruning treatments reduced the crown structure to the uppermost portion of the tree bole, reducing the shading effects, and thus, shrinking the shaded area on the ground by up to 38%, together with the shading intensity. As an alternative, the selective removal of branches reduced the shading effects, while keeping a more similar spatial distribution compared to the unpruned tree. Hence, the virtual pruning of tree structures can support designing and selecting adequate tending operations for the management of light distribution in agroforestry systems. The evidence assembled in this study is highly relevant for agroecosystems and can be strategically used for maintaining, planning and designing integrated tree-crop agricultural systems.

Growth and physiological potential of various turf grass species under graded shade levels

An study was carried out to evaluate the effects of graded shade levels on the growth and quality of turf grass species Cynodon dactylon (Bermuda grass), Zoysia matrella (Manilla grass), Stenotaphrum secundatum (St. Augustine grass), Paspalum notatum (Bahia grass), Paspalum vaginatum (Seashore Paspalum), Dactyloctenium aegyptium (Crowfoot grass), Axonopus affinis (Mat grass/Carpet grass) and Eremochloa ophiuroides (Centipede grass). These species grown under shade nets with different shading intensity of 25%, 50%, and 75% along with control (without shade net) were investigated at Division of Floriculture and Landscaping, IARI, New Delhi during 2017-19. Among the all species, Crowfoot grass and Zoysia found good under reduced irradiance conditionas compared to open conditions, while, St. Augustine, Bahia and Seashore Paspalum performed well from 25-50% reduced irradiance level but these were best under open conditions. Performance of Bermuda grass, Carpet grass and Centipede were not satisfactory under reduced irradiance level.

Effect of Varying Shade Intensities of Green Net on Growth and Stomatal Attributes of Different Ocimum Species

Effect of Varying Shade Intensities of Green Net on Growth and Stomatal Attributes of Different Ocimum Species

Parameter Estimation in a PDE Model for the Spatial Spread of Cocoa Black Pod Disease.

In this paper, we develop an epidemiological model with both environmental (primary infection from the environmental spores reservoir) and direct transmission (secondary infection from an infected host to a susceptible pod). This model simulates the spatiotemporal evolution of cocoa black pod disease caused by Phytophthora megakarya. Since reliable parameter estimation is a central issue for modeling realistic biological systems, we used a mechanistic-statistical approach to estimate model parameters from real observations of a specific cocoa plot. In addition, to refine numerical simulations of the pathosystem, data describing the shade intensity all over the plot were exploited and led to increased model predictions accuracy and also highlighted a higher number of infected pods located in areas of the plot with higher shading intensity. Recommendations in terms of promoting cocoa farming in systems with low shading intensity may be evident if these results are confirmed. Our results also highlight the importance of the environmental spore reservoir in black pod disease dynamics.

Pengaruh Media Tanam dan Intensitas Naungan Terhadap Pertumbuhan Bibit Api-Api (Avicennia alba)

Mangrove forests are ecosystems located in tidal areas in coastal areas, beaches, and small islands. The area of ​​mangrove forests is decreasing due to the conversion of mangrove forests into fishponds, plantations, and timber exploitation. Mangrove ecosystem rehabilitation activities need to be carried out through planting. Avicennia alba is a pioneer mangrove species that grows in mangrove swamp habitats on sheltered coastal locations, as well as in the saltier parts of the coastline. The objectives of this research is to analyze the effect of planting media and shade intensity on the seedling growth of Avicennia alba. The study used a two-factor experimental design in a complete randomized design. The first factor is planting media and the second one in shade intensity. The results showed that the shading intensity most influenced the growth of Avicennia alba seedlings. The variables affected include height, diameter, number of leaves, total wet weight, and total dry weight. The treatment combination that gave the best results was A2N0, that means the planting medium in the form of a mixture of mud, sand and compost and without shade (0% shade).
 Keywords: Avicennia alba, growth, photosynthesis, planting media, shade intensity

Seasonal changes in carbon and nitrogen metabolism of Brachiaria decumbens in a long‐term silvopastoral system

AbstractOur objective was to quantify the metabolites involved in the carbon and nitrogen metabolism of leaf blades of Brachiaria decumbens grown under conditions of intense shade (69%) in the understory of a silvopastoral system (SPS) and compare them to B. decumbens leaf blades grown in an open pasture (OP) under full sunlight. Two treatments corresponding to the specific production system (SPS and OP) were evaluated over four seasons: Spring 2016, Summer 2017, Autumn 2017, and Winter 2017. In the SPS, we observed an increase in the levels of nitrogen‐related metabolites (chlorophyll, nitrate, amino acids and total soluble proteins) and a reduction in carbon‐related metabolites (total soluble carbohydrates, malate, fumarate, starch and sucrose) relative to those in the OP. This pattern of response was also influenced by the seasons, with higher levels of nitrogen‐related metabolites present during seasons with a greater availability of growth resources. In contrast, most carbon‐related metabolites were lower in the spring and summer and higher in the autumn and winter; only sucrose and starch were higher in the spring and winter. Our results demonstrated that intense light restriction in an SPS affects the productivity, longevity and nutritional value of the forage by reducing the levels of metabolites involved in carbon metabolism and increasing the metabolites involved in nitrogen metabolism.

Physiological behavior of Campomanesia xanthocarpa O. Berg. seedlings under flooding and shading

Physiological information about native species, make it possible to know their potential for use in programs to recovery degraded areas. Nowadays climate changes are severe and factors as water and light are involved with plant development and growth. We hypothesized that shading may contribute to adjusting the characteristics of photosynthetic metabolism of Campomanesia xanthocarpa seedlings under flooding. Thus, this work aimed to evaluate the flooding times and shading levels for gas exchanges and the maximal photochemical efficiency of PSII (Fv/Fm) in C. xanthocarpa seedlings. Seedlings were grown under two water regimes (control and flooding), three levels of shading (0, 30, and 70%) and 4 evaluation periods (0, 15, 30, and 45 days). We verified damages to the photosynthetic apparatus and reductions in the efficiency of the photochemical process under flooding and at a high level of shading (70%) in a short period (15 days). However, seedlings showed favourable responses to the adjustment over the 45 days of exposure to those conditions. According to the multivariate analysis, it was possible to identify the relation between photosynthetic rate and stomatal conductance as the main factor of metabolic adjustments in the tolerance of C. xanthocarpa to flooding and high shading intensity. C. xanthocarpa was more sensitive to short periods of flooding conditions and full sun and high level of shading (70%), however, it presented better adjustment responses to flooding periods when associated with 30% shade.

THE EFFECT OF PARANET SHADE ON THE GROWTH AND MORPHOLOGICAL CHARACTERISTICS IN SIX SPECIES OF MANGROVE SEEDLING

In mangrove rehabilitation, nursery operation was required to enhance survival of seedlings prior to field planting. Healthy and mature seed and propagules of six mangroves namely Ceriops tagal, Sonneratia alba, Rhizophora apiculata, S. caseolaris, R. mucronata, and Xylocarpus granatum were planted in paranet shade (0%, 25%, 50%, 75% and 100%) for three months. The research purpose was to study the impact of paranet shade on the growth, and morphologic characteristic in all six mangrove seedlings. Results indicated that 50% paranet shade intensity supported C. tagal, R. mucronata, and S. caseolaris seedlings for the best growth (height and diameter). By contrast, 75% intensity of the shade displayed in the optimal growth, number of leaves, and the leaves area of R. apiculata seedlings. We determined that the best growth of seedlings of X. granatum was acquired in the intensity of shade 100%, contrary with S. alba seedling, showing 0% shade intensity as the best for growth. The tolerance to paranet of mangrove shade plants preceded the sequence of X. granatum (landward species) > R. apiculata > R. mucronata; C. tagal, and S. caseolaris > S. alba (seaward species). The present works generates useful information for restoration efforts in North Sumatra and indicates the value for representative mangrove species of intensely shaded nurseries based on optimum growth and morphological characteristics.

Effects of fruit tree canopy shading on grain filling of intercropping winter wheat.

Fruit tree-wheat intercropping system is the main agricultural production pattern in sou-thern Xinjiang. In this study, almond (Amygdalus communis)-winter wheat (Xindong 20 (Triticum aestivum, var. Xindong 20) intercropping system was used as the research object. Four tree forms of delayed open-central shape (DC), open-center shape (OC), high stem-shape (HS), and semicircle small-canopy shape (SC) and three intercropping distances (wheat intercropping area respectively 1.5, 2.5 and 3.5 m from the tree trunk) were set to create tree canopy shading treatments, with monoculture wheat as the control. The environmental factors and the grain filling characteristic of winter wheat under different treatment conditions were measured, and the correlation between grain filling characteristics and 1000-grain weight and environmental factors was established to provide information for selecting the best management standards and optimizing the intercropping system. The results showed that under the almond tree-winter wheat intercropping system, the PAR, red/far-red light (R/FR), and temperature above the wheat canopy were significantly decreased due to canopy shading, resulting in a significant increase in humidity. The degree of variation was affected by tree form and distance. The PAR decrease degree of the four treatments was DC＞OC/HS＞SC, except for HS. The PAR decrease of the other tree form treatments was 1.5 m＞2.5 m＞3.5 m. The PAR decrease was distributed in the range of 35.5%-86.6%. A cubic polynomial equation represented the grain filling process, and the specific property of grain filling and 1000-grain weight was assessed using the correlation analysis. The decrease in the 1000-grain weight in the intercropping system was closely associated with the decreases in average grain-filling rate (V), maximum grain-filling rate (Vmax), effective grain-filling duration (Se), and effective grain-filling duration (Vs). The shortening of Se and the reduction in the grain filling rate were related with the reduction in the PAR incidence above the wheat canopy. In the fruit tree-winter wheat intercropping system, the reduction of PAR, dry matter accumulation after flowering, and Se were reduced by tree canopy shading consequently for the decrease in the 1000-grain weight of the intercropping wheat. When the distance between the intercropping area and the tree trunk was greater than 75% of tree height, and shading intensity was less than 35.5% of the natural light intensity, the intercropping with the almond tree could increase the 1000-grain weight of wheat by increasing the effective grain-filling duration.

Ultrasonic dyeing of wool fabric with aqueous extract of Ratanjot (Onosma echioides) natural dye

The purpose of this study is to compare the conventional and ultrasonic dyeing methods in terms of its colour strength and colour fastness properties of wool fabric dyed with Ratanjot root. The results suggested that dyeing of wool fabric with natural dye Ratanjot (Onosma echioides) using ultrasonic waves, significantly improved the dye uptake percentage to 12.31 per cent from conventional heating methods. The fastness grade were found to be higher with ultrasonic than conventional heating. Additionally, the fabric dyed using ultrasonic waves gave a deeper shade and good colour intensity even at lower dyeing time (75min) and temperature (60°C). Therefore, ultrasound wave represents a promising technique for increasing diffusion of dye by the effect of cavitation, as well as for improving the effectiveness of processes when compared to conventional heating

Altitude, shading, and management intensity effect on Arabica coffee yields in Aceh, Indonesia

Abstract The productivity of Arabica coffee in the Gayo Highlands, Aceh, Indonesia is far below its potential because of climate change and inadequate agricultural practices. To develop a strategy on sustainable coffee yield and improvements of smallholder farming systems, we investigated coffee productivity in three classes of shade densities and three classes of total management intensities index (TMI) along six altitude gradients (1,000–1,600 m above sea level) over 234 farmers’ plots. Coffee productivity was significantly affected by altitude, shade density, and TMI. Our results showed a stronger positive altitudinal effect with coffee productivity in middle and higher altitudes than in lower altitudes and were related to shade density and TMI. Increasing elevation of coffee plantation from lower to middle altitudes and shade from low to medium density increased in coffee productivity but further increase to higher altitude seemed to depress coffee productivity. Increasing TMI positively increased coffee productivity across altitudes. Shade density and TMI played significant roles in coffee productivity in lower altitudes; therefore, coffee farmers have to increase the shade to medium or higher density and at the same time improve plantation management to medium or high TMI.

Interactions between drought and shade on the productivity of winter pea grown in a 25‐year‐old walnut‐based alley cropping system

AbstractIn the face of climate change, more frequent drought events are expected in the Mediterranean regions. Alley cropping is an agroforestry practice that represents a promising adaptation strategy to sustain yield productivity under drier conditions. However, the presence of trees limits the productivity of the intercrop by reducing light availability and by competing for soil water resources, which could potentially exacerbate the yield losses due to drought conditions. Furthermore, the effects of co‐occurring drought and shade stresses on annual crops are still poorly understood. To tackle this issue, we performed a rainfall manipulation experiment on winter pea (Pisum sativum L.) grown in full‐sun conditions (agricultural control) and under different levels of shade in a 25‐year walnut‐based alley cropping system located in southern France. We evaluated first the effect of trees on light and water availability, and we then studied the effects of early drought (135 mm excluded from April to the end of May) and light conditions on crop performances and yield components. At 3.5 m from the tree line, light availability was reduced on average by 19% at south and 35% at north of trees over the entire crop cycle and mostly after tree budburst. The impact of trees on soil water content in the crop root zone was weak thanks to the good complementarity of the respective root systems. Under normal rainfall conditions, tree shade decreased pea yield from −25% to −77% compared to full‐sun conditions. In case of spring drought, pea yield was decreased by −22% in full‐sun conditions. The negative effect of tree shade was reduced and decreased pea yield only by −1% to −47%. Under the most intense shade conditions, pea yield was even higher under drought than in normal rainfall conditions. The analysis of crop dynamics and yield components revealed that the vegetative development of pea ceased under drought to the benefit of biomass allocation towards the reproductive organs. Pea yield was less impacted by tree shade under spring drought because yield elaboration relied less on the success of pod set, sensitive to shade and, more on grain filling, improved in case of early drought event. This study supports the hypothesis that agroforestry systems may be more resilient in the case of early drought.

Tall fescue is a superturfgrass: Tolerance to shade conditions under deficit irrigation

To evaluate the morpho-physiological characteristics of some cool-season turfgrass species under shade stress, an experiment was conducted outdoor in two subsequent years. Then, tall fescue, as the best-recognized turf from the former test, was exposed to combined drought and shade stress, aiming to measure to what extent shade can decrease turfgrasses water consumption and alleviate drought effects. The first test included 35 treatments at 7 different levels of continuous and temporal shade conditions in the morning and afternoon (60% and 80%) and full sunlight, and 5 cool-season turfgrass species, i.e., tall fescue ( Festuca arundinacea Schreb.), red fescue ( Festuca rubra L.), perennial ryegrass ( Lolium perenne L.), Kentucky bluegrass ( Poa pratensis L.) and sheep fescue ( Festuca ovina L.)]. The second test was consisted of 9 treatment, including 3 different irrigation intervals (i. e. 3, 6, and 9 days), 3 shade stress (i.e. full sunlight, 60% and 80% permanent shade), and 3 replications. Seeds of different cool-season turfgrass species were sown in April 2015 and 2016 in a loamy soil. Treated turfgrasses were evaluated for morpho-physiological and biochemical characteristics. Results showed that in the first test tall fescue has the highest quality in terms of morpho-physiological characteristics at a high level of shade stress (80% continuous shade). Perennial ryegrass and Kentucky bluegrass showed weak tolerance to shade stress conditions. The 80% constant shade had the greatest influence on turfgrass qualitative and quantitative traits, but in some cases did not show a significant difference between temporal shades. Turfgrasses quality decreased by increasing the intensity and duration of shade; however tall fescue was an excellent turfgrass species under shade stress conditions. Although visual quality, tiller density, and total chlorophyll content of tall fescue were significantly reduced by less frequent irrigation, they were improved by shade treatment compared with control plants. In addition, tall fescue has the highest amount of proline, catalase activity, starch, and reducing sugars under 9 days of drought and 60% shade stress. This is the first report of the interaction of shade and drought stress on the biochemical and morpho-physiological responses of tall fescue plants.

Tree species richness modulates water supply in the local tree neighbourhood: evidence from wood δ13C signatures in a large-scale forest experiment.

Biodiversity is considered to mitigate the adverse effects of changing precipitation patterns. However, our understanding of how tree diversity at the local neighbourhood scale modulates the water use and leaf physiology of individual trees remains unclear. We made use of a large-scale tree diversity experiment in subtropical China to study eight tree species along an experimentally manipulated gradient of local neighbourhood tree species richness. Twig wood carbon isotope composition (δ13Cwood) was used as an indicator for immediate leaf-level responses to water availability in relation to local neighbourhood conditions and a target tree's functional traits. Across species, a target tree's δ13Cwood signatures decreased progressively with increasing neighbourhood species richness, with effects being strongest at high neighbourhood shading intensity. Moreover, the δ13Cwood-shading relationship shifted from positive (thin-leaved species) or neutral (thick-leaved species) in conspecific to negative in heterospecific neighbourhoods, most likely owing to a lower interspecific competition for water and microclimate amelioration. This suggests that promoting tree species richness at the local neighbourhood scale may improve a tree's local water supply with potential effects for an optimized water-use efficiency of tree communities during drought. This assumption, however, requires validation by further studies that focus on mechanisms that regulate the water availability in mixtures.